Powering intelligent instruments with Lua scripting

As the power of the integrated processors that control today's instruments continues to climb, instrument vendors will increasingly add features that allow users to utilize the added intelligence by embedding custom applications directly onboard the instrument. For the test, measurement and automation industries, this paradigm is a complement to, among other things, the advent of synthetic instruments that can ldquobe anything you want,rdquo the frequent use of mezzanine type hardware and the rise of the LXI specification in which instrument to instrument messaging allows one instrument to control and communicate with another without the necessity of a host PC. There are various approaches the instrument vendor can take to permit users to develop embedded applications to be run on the instrument processor. Arguably the most advantageous approach, to both the vendor and customer, is to embed a high level scripting language allowing the user to easily develop scripts to perform instrument based operations. The Lua scripting language is a compact, full featured scripting language that is easily portable and seamlessly integrates into embedded designs. Written in pure ISO ANSI-C, the Lua interpreter and Lua libraries have been successfully ported to a large number of platforms, big and small, and with and without advanced operating systems such as Windows and Linux. Lua contains an API for interfacing directly to and from the instrument's embedded firmware and includes a full suite of libraries. Further, Lua is extendable. Thus, in addition to embedding the language interpreter and libraries, the vendor can implement custom libraries and various other custom utilities to increase the flexibility of the system and enhance the capabilities of the user developed scripts. This paper studies the use of Lua in intelligent instrumentation. It discusses features that provide flexibility and power to users embedding applications onboard instruments and it presents some real world applications of the technology.